The crustaceans burrow Sinusichnus sinuosus from the Oligocene-Miocene carbonate deposits of eastern Amazonia

Abstract

Sinusichnus Gibert 1996 Gibert, J. M. d. 1996. “A New Decapod Burrow System from the NW Mediterranean Pliocene.” Revista Española de Paleontología 11: 251–254. [Google Scholar] is recorded for the first time in the Oligocene-Miocene Pirabas Formation of Northern Brazil. In these Oligocene-Miocene carbonate deposits, Sinusichnus sinuosus is characterized by horizontal, highly regular sinusoidal burrow systems with T- and H-shaped branching points. The main difference between the S. sinuosus described herein and other occurrences worldwide is the anomalous diameter of the burrows (4 to 10?cm). These trace fossils occur in organic matter-rich, wackestone/packstone and laminated mudstones interbedded with boundstones deposited in an inner carbonate platform paleoenvironment. The exceptional size of the studied S. sinuosus could have been associated to the producer’s size, which may be attributed to construction by large crustaceans, similar to fossils found within the Pirabas Formation. Also, the sinusoidal morphology and retrusive spreiten could be a result of the fodinichnial/domichnial behavior.     

Feeding and locomotor rhythm of the ornamental cichlid fish Amatitlania sp. in different social groups

The aim of this study was to evaluate the feeding activity and the rhythm of daily locomotor activity of the convict cichlid (Amatitlania sp.) kept in different social groups under a self-feeding system. A total of 120 animals was distributed among six repetitions of four social groups, as follows: group 1 with one male and one female per tank; group 2 with three males and three females per tank; group 3 with six males per tank; and group 4 with six females per tank. Feeding activity (FA) and locomotor activity (LA) were evaluated using photoelectric presence-sensors connected to automatic feeders. The fish were fed a commercial extruded diet (46% crude protein and 3600 kcal kg⁻¹ of digestible energy). Animal growth was evaluated for all groups. After 30 days of experimentation, the fish stabilized their demands by adjusting their consumption. Amatitlania sp. showed predominantly diurnal FA and LA. All groups showed a peak of activity when the light was turned on and when it was turned off. In summary, FA and LA of Amatitlania sp. are predominantly diurnal and independent of social group. Pairs and groups of males and females together consume less food in relation to groups of one sex or the other due to reproductive behaviour. On the other hand, groups of only males or females consume more food because they lack reproductive stimuli and thus prioritize growth. These results may support good feeding management practices for this ornamental cichlid. Studies relating feeding behaviour with different social groups are of great importance for determining effective feeding strategies for this species in captivity. Thus, such a study assists in a more efficient production of Amatitlania sp.     

Autoanticorps anti-protéines “citrullinées” dans la polyarthrite rhumatoïde

En 1964, RLF Nienhuis et coll. [1] décrivaient, dans plus de deux tiers des sérums de patients atteints de polyarthrite rhumato?de (PR), des anticorps marquant en immunofluorescence indirecte des granules périnucléaires présents dans les cellules les plus superficielles de la muqueuse jugale humaine. Ces anticorps étaient appelés “facteur anti-périnucléaire” (antiperinuclear factor: APF) par analogie avec le “facteur” rhumato?de (FR) qui constituait alors l’unique marqueur biologique de la PR. Quinze ans plus tard, une équipe anglaise, BJJ Young et coll. [2] montrait qu’environ la moitié des patients atteints de PR présentait des anticorps circulants marquant en immunofluorescence indirecte la couche cornée de l’épithélium malpighien qui revêt l’œsophage de rat. Les kératines étant les protéines les plus abondantes et les mieux connues dans cette couche épithéliale, les auteurs appelaient ces anticorps “anti-kératine” (antikeratin antibodies: AKA), en l’absence de tout élément biochimique permettant d’affirmer la nature de l’antigène reconnu.